If you are currently undergoing issues with your eye health, it never hurts to know a thing or two about the eyes and how they work. Knowing more about your eyes’ anatomy may help you be calmer about upcoming treatments, as you are more informed of the process. Below we will discuss some of the different parts of the eye, and how they work together to help us see.
The cornea is the outermost layer of the eye which is primarily responsible for focusing light. It consists of 5 layers: deeper layers which exist to give strength to the eye, and outer layers which act as a kind of “shield” to the elements. The outer layer of the cornea is quite resilient, and is often able to repair itself within a few days of suffering a minor injury.
The pupil is the black circle in the center of the eye. Its primary function is to monitor and control the amount of light that comes into the eye. When there is a lot of light, the pupil contracts to keep the light from overwhelming the eye’s delicate sensors. When there is very little light, the pupil expands so it can absorb as much light as possible. This is why your pupils look very large in near-darkness, and very small under bright lights.
The iris is the colored part of the eye, but its function is far more than cosmetic. The iris contains muscles that contract or expand in order to adjust the size of the pupil. It is pigmented with a wide variety of colors, including brown, hazel, green, gray, and blue; however, the only pigment that contributes significantly to color is the dark pigment melanin. The amount of eumelanin (brown/black melanins) and pheomelanin (red/yellow melanins) are what determine our eye color. More of the former is found in brown-eyed people, and more of the latter is found in blue and green-eyed people.
The retina is a thin layer of tissue that lines the back of the eye, located near the optic nerve. The purpose of the retina is to receive light that the lens has focused, convert it into neural signals, and send these signals on to the brain for visual interpretation. The retina is composed of several layers, including one that contains specialized cells called photoreceptors. There are two types of photoreceptor cells in the human eye — rods and cones. Rod photoreceptors detect motion, provide black-and-white vision and function well in low light. Cones are responsible for central vision and color vision and perform best in medium and bright light.
The lens sits behind the pupil, and enables the eyes to focus on small details, like the words in a book. The lens is in a constant state of adjustment, as it becomes thinner or thicker to accommodate the input it receives. As people age, their lenses lose a lot of their elasticity, which often results in conditions such as cataracts wherein the lenses cannot adjust to their surroundings as well as they used to.
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